1. Field of the Invention
This invention relates to an improved sheet inverting system, and more particularly, to a compact rotator/inverter that accomplishes improved handling of variable sized sheet within minimal space requirements.
2. Description of Related Art
Although a sheet inverter is referred to in the copier/printer art as an xe2x80x9cinverterxe2x80x9d, its function is not necessarily to immediately turn the sheet over (i.e., exchange one face for the other). Its function is to effectively reverse the sheet orientation in its direction of motion. That is, to reverse the lead edge and trail edge orientation of the sheet. Typically in inverter devices, the sheet is driven or fed by feed rollers or other suitable sheet driving mechanisms into a sheet reversing chute. By then reversing the motion of the sheet within the chute and feeding it back out from the chute, the desired reversal of the leading and trailing edges of the sheet in the sheet path is accomplished. Depending on the location is and orientation of the inverter in a particular sheet path this may, or may not, also accomplish the inversion (turning over) of the sheet. In some applications, for example, where the xe2x80x9cinverterxe2x80x9d is located at the corner at a 90xc2x0 to 180xc2x0 inherent bend in the copy sheet path, the inverter may be used to actually prevent inverting of a sheet at that point, i.e., to maintain the same side of the sheet face-up before and after this end in the sheet path. On the other hand, if the entering and departing path of the sheet, to and from the inverter, is in substantially the same plane, the sheet will be inverted by the inverter. Thus, inverters have numerous applications in the handing of either original documents or copy sheets to either maintain, or change, the sheet orientation.
Inverters are particularly useful in various systems of pre or post collation copying, for inverting the original document, or for maintaining proper collation of the sheets. The facial orientation of the copy sheet determines whether it may be stacked in forward or reversed serial order to maintain collation. Generally, the inverter is associated with a by-pass sheet path and gate so that a sheet may selectively by-pass the inverter, to provide a choice of inversion or non-inversion. However, it is particularly difficult to use inverters of this type in small copiers that take advantage of short edge paper transport to reduce costs by reducing overall machine depth.
Short edge feeding creates a problem in sheet inversion when the duplex function is added to the machine. Some standard inverter techniques result in the top of the duplex image occurring at the bottom of the simplex image.
U.S. Pat. No. 4,500,086 issued Feb. 19, 1985 to Gerald M. Garavuso, shows a rotating inverter mechanism that includes a chute positioned to deflect a sheet from a horizontal plane downward as the sheet is rotated by action of primary and secondary rollers so that rotation can be accomplished in a distance no wider than the width of the sheet.
A compact inverter is shown in U.S. Pat. No. 5,374,049 issued Dec. 20, 1994 for reversing the lead and trail edges of a sheet. The inverter includes a reversible roller of about 2 inches in diameter onto which a sheet is scrolled and subsequently unscrolled, thereby reversing the lead and trail edges of the sheet.
In U.S. Pat. No. 5,415,391 issued May 16, 1995 to Wong et al. an inverter is shown for inverting sheets using the existing paper path to invert the sheets. A sheet is inverted by being deflected into a channel formed between a turnaround roller and a baffle. The sheet is driven by the turnaround roller back into the original paper path in a direction opposite to the incoming direction of the sheet.
Even though the above-mentioned inverting systems are useful, there is still a need, in printers that include an image output terminal (IOT), to provide a number of features (e.g., head to toe marking) requiring an image be rotated 180xc2x0 with the IOT trays supporting a wide range of sheet sizes including A3 and 11xc3x9717.
Accordingly, pursuant to the features of the present invention, a sheet manipulator is disclosed that answers the above-mentioned problem by providing a device that can rotate a sheet 180xc2x0 or invert the sheet, if required. The sheet manipulator includes a horizontal cylinder. A front image output sheet wraps around the horizontal cylinder (turning counter-clockwise), entering the cylinder from the bottom. The cylinder then rotates 180xc2x0 with the wrapped sheet. Continued counter-clockwise rotation of the cylinder will now unwrap the sheet from the cylinder and drive it away from the cylinder. In order to accomplish inversion, a deflector is raised in front of the cylinder. A sheet is directed over the top of the cylinder by the deflector as the cylinder turns clockwise. The sheet wraps around the cylinder and thereafter, the cylinder is rotated counter-clockwise resulting in the sheet exiting the cylinder at the bottom and after having been inverted. This and other features and advantages of the invention are described in or apparent from the following detailed description of the exemplary embodiments.